3-way light switch, 2 'hot' lines

brian__mJune 1, 2014

So, I'm trying to fix lots of PO issues in a new-to-me, 1930's home. Today I'm working on 2 banks of 3 way switches. I've seen this error before, one switch will turn the light on and off, the other will Only work if the first switch is "on". Since 3-ways are newish to me, I was following this guide:


And it was spot on for all but 1 of the light circuits (sets of switches). The 2 remaining switches Both have a hot/120v white coming into them. So, since that threw me for a loop and I don't have online access from the house I came home to search, but I'm not finding anything.

What I'd like to know is if there is Ever a time when this would be correct? If yes, care to explain the correct wiring? If no.. well, I guess I'll be correcting the issue next weekend (10th wedding anniversary today, taking a week long vacation to hike, camp, and hit micro-breweries in NC).

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Ron Natalie

Yes. There is/was an exception to the rule that restricts white to the grounded (neutral) conductor for wiring switches.

To get back to the original problem, one of he switches most likely is wired wrong.

If both switches are properly three ways, my guess is that someone has one of the traveler / common wires swapped. I'd try swapping the wires on the switch (most likely the one that is contingent on the first one). There's really only three ways it can be hooked up...so try the other two.

You must identify which terminal on the switch is the common terminal however (and try that on the other two wires). The other two terminals are effectively interchangeable.

    Bookmark   June 1, 2014 at 8:57PM
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Yes as ronnatalie stated there is an exception, when the power is brought to the light fixture,then the white of the(2) wire going to the switch is connected to the "hot" or black power wire.This wire(white) is used to bring the power to the switch, then the black(2) wire brings the power back to the light from the switch to turn it on......This 2 way switch connection is wired different from the 3 wire light connection as stated below. One example of a 3 way switch connection is: the black power wire bringing power to the switch is installed on the black screw of # (1) 3 way switch, and the white,neutral in this case is connected to white wire of the 3 wire,( blk,red and white), going from #(1) switch to #(2) switch,and connects to the white 2 wire coming from the light.The black wire also coming from the light connects to the "black" screw on #(2) switch. The remaining red and black wires, "travelers", from the 3 wire connect to the other 2 screws in the same position on both switches, e.g,black on the top and red on the bottom of both switches. This is the sequence if the power and light fixture wires are at different switches. If they are in the same switch area, there is another sequence. Hope this helps

    Bookmark   June 2, 2014 at 7:35PM
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